UV Contact and UV Proximity Lithography

Negativsprühlack strukturiert für Lift-Off Prozess in 160 µm tiefen Si-Kavitäten.
© Fraunhofer ENAS
Negative spray resist structured for lift-off process in 160 µm deep Si cavities.
Strukturierter Permanent-Trockenfilmresist nach dem Hardbake (200 °C).
© Fraunhofer ENAS
Structured permanent dry film resist after hardbake (200 °C).

For UV contact and proximity exposure, a Mask Aligner MA200 from SUSS MicroTec is used. It features two different alignment systems: frontside and backside alignment. To ensure the protection of double-sided structures such as those in MEMS, substrates are transported and processed through the system with an edge-handling system. After exposure, the coated substrates are developed using dip or puddle development.

Before exposure, the 150 mm and 200 mm substrates (Si wafers, glass wafers, composites of Si-Si or Glass-Si, etc.) must be coated. This is done using spin-on or spray coating. Both positive and negative resists are used, achieving layer thicknesses from approximately 900 nm to 60 µm (100 µm SU-8). Dry film resists can also be used on wafers via lamination. The generated resist masks are needed for various subsequent processes, including wet and dry etching, lift-off, electroplating (aqueous and ionic electrolytes), bonding (SU-8), etc.

Highlights:

  • Mix and match Mask Aligner with projection lithography (intralevel and interlevel)
  • Double-sided lithography (also possible in combination with a stepper)
  • Spray coating (positive and negative resist)
  • Exposure in cavities
  • Permanent dry film resist, e.g., for microfluidics or bioapplications.